Larynx 1


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  • This cartilage has two alae/wing which meet anteriorly, they form a depression called the THYROID NOTCH before meeting at the protuberance of the Adam’s apple or laryngeal prominence. Posteriorly, each wing has a superior cornu (extending upward about 2 cm) and inferior cornu (articulates w/cricoid cartilage below; ONLY DIRECT ARTICULATION, all others being maintained by muscles or ligaments)Ossifies at 20-30 years of age, begins in the inferior margin and progress cranially
  • Ossifies after the thyroid cartilage, first part to be calcified being the superior portion (w/c can be mistaken for a foreign body) Calcification progresses caudally.Lamina – flat portion of the ring llocated posteriorly and extends upward to form the POSTERIOR border of the larynxOnly complete annular support of the laryngeal skeleton; preservation essential to maintain the enclosed airways.Level: Adult: C6-C7 Children: C3-C4Posterolaterally, cricoid articulates w/ Inferior cornu of the thyroid cartilage, which forms true synovial joints (permit a ROCKING action of the cricoid cartilage on the thyroid cartilage and a slight anteroposterior SLIDING motion (cricoid cart. Supports the 2 arytenoid cartilages on posterosuperior aspect)
  • Attached to the INSIDE of the thyroid cart. Anteriorly and projects upward and backward above the laryngeal opening.Petiole – small narrow portion of the glottis that is attached to the thyroid cart.The epiglottis is attached to the hyoid bone by the hyoepiglottic ligament. To the posterior part of the tongue by the median glossoepiglottic fold. To the sides of the pharynx by the lateral glossoepiglottic folds. To the thyroid cartilage by the thyroepiglottic ligament.The mucous membrane covering the epiglottis is reflected to the posterior part of the tongue as one medial and two lateral glossoepiglottic folds. Between these folds are depressions called epiglottic valleculae.
  • Calcify at the 3rd decade (Hyoid – ossifies fr. 6 centers shortly after brith, complete by 2 years of age)Arytenoids rest on the upper edge of the cricoid lamina at the posterior border of the larynx
  • Cricothyroid Joint - Synovial joint with a capsular ligament bet. Inferior cornu of the thyroid cartilage and the facet on the cricoid cartilage at the junction of the arch and lamina. Rotation – thru a transverse axis Gliding – slightlyCricoarytenoid Joint - Synovial joint with a capsular ligament bet. Base of the arytenoid cartilage and the facet on d upper border of the lamina of the cricoid cartilage Rotation – arytenoid rotates on a vertical axis, vocal process moves medially or laterally Gliding – arytenoids move toward or away from each other. (strong posterior cricoarytenoid ligament prevents excessive movements of the arytenoids on the cricoid)
  • Thyrohyoid m&L –attach thyroid cart. To hyoid bone
  • Obvious from its name, the CT m&L connect the thyroid and cricoid cart.Cricothyrotomy – little fear of bleeding; however becoz of proximity to the vocal cords, this space shld not be used for prolonged intubation, as scar tissue may be produced.
  • Elastic m.-lies beneath the laryngeal mucosa, Fibrous framework of the larynxVentricle of the larynx (ventricle of Morgagni)Quad membrane - Boundaries: extending from LATERAL margin of epiglottis to arytenoid and corniculate cart., and INFERIORLY to the false cord.
  • Median cricothyroid ligament – thickened anteior part of conus elasticusVocal Ligament – is d free upper edge of the conus elasticus (strongest part), forms the framework of the vocal cordThyroepiglottic ligament – ataches epiglottis to the thyroid cartilage
  • Divided into 3 parts by 2 folds of mucous membrane, namely the true and false cords.Vestibule – lies bet. Inlet and edges of false cordsVentricle (Morgagni) - Deep, spindle-shaped recess bet. True and false cords, lined by a mucous membrane that is covered externally by thyroarytenoid muscleSubglottic space – lies bet. True VC and lower border of cricoid cartilage
  • Saccule – conical pouch that ascends fr anterior part of the ventricle, lies bet. Inner surface of thyroid cartilage and false cord; has numerous mucous glands open into the surface of its lining mucosa for lubricating the vocal cords.Glottis – space bet. Free margin of the true VC, opening/aperturePosterior glottic chink in adult: 18-19mm; New born: 4mm; total glottic chink in a newborn: 14mm2
  • Subglottic space – lies bet. True VC and lower border of cricoid cartilagePreepiglottic space – a wedge-shaped space lying in front of the epiglottis
  • False cords – upper set of two horizontal folds on each side of the laryngeal cavity.TVC – covering epith. Is closely bound down to underlying vocal ligament, blood supplu here is poor hence the pearly white appearance of the vocal cords in life.
  • Intrinsic muscles, all are paired except Interarytenoid m.Larynx moves up during swallowing, down after.The extrinsic muscles move the larynx as a whole. The infrahyoid muscles or straps (omohyoid, sternohyoid, and sternothyroid) are depressors of the hyoid bone and the larynx, whereas the suprahyoid muscles (stylohyoid, digastric, mylohyoid and geniohyoid) and the stylopharyngeus are elevator of the hyoid bone and larynx.
  • Sternothyroid Muscle - a thin muscle located deep to the sternohyoid muscle, and is shorter and wider than it.Inferior attachment: posterior surface of manubrium of sternum.Superior attachment: oblique line of thyroid cartilage.Innervation: C2 and C3 by a branch of the ansa cervicalis.It depresses the hyoid bone and larynx after it has been elevated by muscles during swallowing and vocal movements.It also pulls the thyroid cartilage away from the hyoid bone, thereby opening the laryngeal orifice.
  • Muscles controlling the laryngeal inlet
  • Muscles controlling Movements of the Vocal CordsELN –ext laryngeal branch from SLN(CN X)ILN –inferior laryngeal nerve from RLN (CN X)
  • Muscles controlling Movements of the Vocal CordsELN –ext laryngeal branch from SLN(CN X)ILN –inferior laryngeal nerve from RLN (CN X)
  • RLN – longer course on L than R, L: turns around arch of aorta, R: around subclavian arteryNucleus ambiguus – somatic motor nucleus of CN IX, X, XI - supplied by PICA (fr. Veterbal a.) and AICA (fr. Basilar artery)
  • Generally, Lymg drainage from each half of larynx is SEPARATE, LITTLE CROSSOVER/MIXING, although it does cross the midline in supra- and infra-glottic areas.Contralateral drainage more likely in INFRAGLOTTIC areas; ergo, less consistent patterns of mets. Lymphatics arising from larynx drain mainly into deep cervical LNVocal cord contain SCARCELY any lymphatic channels
  • Margins of aryepiglottic folds – none on he free edges of the vocal cordsReinke’s layer of connective tissue – lies immediately under the epith. Of larynx and superficial to elastic layer. NO GLANDS BENEATH AND NO LYMPH VESSELS IN IT.
  • Closure of glottis – helps to increase intrathoracic and intraabdominal pressure and aids in lifting, digging, defecation, vomiting, urination or childbirth
  • Prevents entrance of ANYTHING but AIR into the lung
  • By active muscular dilatation of the laryngeal aperture – meaning by opening of the glottis, which occurs with rhythmic bursts of activity of RLN.Phasic inspiratory abduction – posterior cricoarytenoids – synchronous with respirationPhasic inspiratory contraction – cricothyroid m. (vocal cord adductor and isotonic tensor) –increases AP diameter of of glottic chink.*both are driven by medullary respiratory center
  • Cricothyroid muscles position the vocal cords near midline by isotonic tensionAs pitch increases, true vocal cords lengthen and tense isotonically thru the action of cricothyroid musclesCord thinning is produced by thyroarytenoid action, which increases internal tension of true cord(Extrinsic laryngeal muscles also may affect pitch i.e. sternothyroid)
  • Larynx 1

    1. 1. Laryngeal Cartilages Paired  Unpaired:  Arytenoid  Thyroid cartilage cartilage  Cricoid cartilage  Corniculate  Epiglottis cartilage  Cuneiform cartilage
    2. 2. Thyroid Cartilage Hyaline cartilage Largest Encloses the larynx anteriorly and laterally Two alae, laryngeal prominance, thryroid notch, inferior and superior horn, oblique line, thyrohyoid membrane Ossification
    3. 3. Cricoid Cartilage  Hyaline cartilage  Strongest  Shape: Signet ring  Ant. arch and post. lamina  Only complete annular support of the larynx  Articulates w/ Inferior cornu of the thyroid cartilage  Cricothyroid and cricotrachel ligament
    4. 4. Epiglottis Fibroelastic cartilage Leaf-shaped structure Forms the sup. Part of the ant. Wall and sup. margin of the inlet Petiole – small narrow portion of the glottis Thyroepiglottic ligament Hyoepiglittic membrane Medial and lat. Glossoepiglottic folds, epiglittic valleculae Epiglottic tubercle
    5. 5. Arytenoid Cartilage Mostly hyaline cartilage Responsible for opening and closing of the larynx Shape: three sided pyramidal Apex – aryepiglottic fold Muscular process – post. and lat. Cricoarytanoid muscle
    6. 6. Corniculate Cartilages Fibroelastic Small cartilages above the arytenoid and in the aryepiglottic folds
    7. 7. Cuneiform Cartilages Firboelastic cartilages Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds Triyicial cartilage in thyrohyoid membrane
    8. 8. Laryngeal Joints Cricothyroid Joint  Cricoarytenoid Joint  Between inferior cornu of  bet. base of the arytenoid the thyroid cartilage and cartilage and the facet on facet on the cricoid the upper border of the cartilage at the junction of lamina of the cricoid the arch and lamina cartilage  Two movements: rotation,  Two movements: rotation, gliding sliding, tilting Result in changes in the Result in approximating, length of the vocal folds tensing and relaxing the vocal folds
    9. 9. Laryngeal Ligaments Extrinsic  Intrinsic  Quadrangular  Thyrohyoid membrane and ligaments membrane  Conus elasticus  Cricothyroid membrane and (cricovocal ligaments membrane)  Median cricothyroid  Cricotracheal ligament ligament  Epiglottis  Vocal Ligament  Thyroepiglottic lig.
    10. 10. Extrinsic Ligaments Thyrohyoid membrane  pierced on each side by: 1. Superior laryngeal vessels 2. Internal branch of superior laryngeal nerve  Median thyrohyoid ligament – thickened median portion  Lateral thyrohyoid ligament – thickened posterior border - where cartilago triticea is often found – helps to close the inlet of the larynx during swallowing
    11. 11. Extrinsic Ligaments  Cricothyroid membrane and ligaments  The fibrous median cricothyroid ligament produces a soft spot and it is at this point the airway is closest to the skin and is most accessible  May be pierced for emergency cricothyrotomy tracheotomy
    12. 12. Extrinsic Ligaments Cricotracheal Ligament  Attaches the cricoid cartilage to the first attached ring Epiglottis  suspended in position by membranous connections to the hyoid bone, thyroid cartilage and base of the tongue
    13. 13. Intrinsic Ligaments Fibro elastic membranes  Divided into upper and lower parts by the ventricle of the larynx Quadrangular membrane  Upper part of the elastic membrane  Boundaries  Epiglottis , arytenoid, corniculate cartilage, false cord  Free inf. margin constitute the vestibular ligament, covered loosely by vestibular fold
    14. 14. Vocal ligament Extend from the junction of the laminae of the thyroid cartilages to vocal process of arytanoid It forms the skeleton of the vocal fold and the free edge of the conus elasticus
    15. 15. Intrinsic Ligaments Conus elasticus (cricovocal membrane)  Composed mainly of yellow elastic tissue  Boundaries  Inferior: superior border of cricoid cartilage  Superoanterior: deep surface of angle thyroid cartilage  Superoposterior: vocal process of arytenoid cartilage Thyroepiglottic ligament
    16. 16. Cavity of the Larynx Divided into 3 parts:  Vestibule  Ventricle  Infraglottic cavity (subglottic space)
    17. 17. Vestibule – boundaries:  Anterior: posterior surface of epiglottis  Posterior: interval between arytenoid cartilages  Lateral: inner surface of aryepiglottic folds and upper surfaces of the false cord
    18. 18. • Ventricle • Saccule – conical pouch at anterior part Vocal cords, Glottis Adduction:  Abduction: Phonation, slit-like appearance Respiration, wide and triangular
    19. 19.  Subglottic space – between vocal cords and lower border of the cricoid Preepiglottic space – a wedge shaped space lying infront of the epiglottis  Boundaries:  Anterior: thyrohyoid membrane  Anteroasuperior: hyoid  Superior: vallecula  Posterior: part of the epiglottis  Lateral: hyoepiglottic ligament
    20. 20.  False Cords (ventricular bands), vestibular folds  Anteriorly: angle of the thyroid cartilage  Posteriorly: bodies of the arytenoid cartilage  Space between them – rima vestibuli  Protect from entering food particles to the larynx  True cords, vocal folds  Voice production  Protection of lower respiratory tract  Anteriorly,: angle of thyroid cartilage  Posteriorly: vocal processes of the arytenoid cartilages  Enclose vocal ligament, and a major part of the vocalis muscle  Space between them – rima glottis
    21. 21. Laryngeal Muscles Extrinsic Muscles  Intrinsic Muscles  Depressor group –  Muscles of the inlet of the infrahyoid muscles larynx – Transverse and oblique arytanoid,  Elevator group aryepiglottic, thyroepiglottic Suprahyoid muscles,  Muscles of the vocal folds stylopharyngeus muscles Adductors - lateral  Thyrohyoid muscle cricoarytenoid Abductors – post. Cricoarytenoid Tensors – cricothyroid Relaxers – Thyroarytanoid (one band of inferior deeper fibers are
    22. 22. Depressor Origin Insertion Action musclesSternohyoid (C2, manubrium of oblique line of the depresses/stabilizesC3) sternum and thyroid cartilage the hyoid bone medial end of clavicleThyrohyoid (C1) oblique line of the lower border of the elevates the larynx; thyroid cartilage hyoid bone depresses/stabilizes the hyoid boneOmohyoid (C2, superior border inferior border of depresses, retractsC3) of scapula near hyoid bone and steadies the the hyoid during suprascapular swallowing and notch speaking
    23. 23. Elevator Origin Insertion Action musclesGeniohyoid inferior mental body of hyoid pulls the hyoid bone spine of mandible bone anterosuperiorly, and shortens(C1) the floor of the mouth and widens the pharynxDigastrics anterior belly- intermediate depresses the mandible and digastric fossa of tendon to body raises the hyoid bone. Also, it(Ant. CN V; mandible, and greater horn steadies the hyoid bone duringPost. N. VII) posterior belly- of hyoid bone swallowing and speaking mastoid notch of temporal boneMylohyoid mylohyoid line of raphe and body elevates the hyoid bone, floor of mandible of hyoid bone the mouth and the tongue(V) during swallowing and speakingStylohyoid styloid process of body of hyoid elevates and retracts the hyoid the temporal bone bone, thereby elongating the(VII) bone floor of the mouth
    24. 24. Elevator Origin Insertion Action musclesStylopharyngeus styloid posterior and elevates the pharynx and(CN IX) process of superior borders of larynx and expands the temporal thyroid cartilage with sides of the pharynx bone palatopharyngeus muscleSalpingopharyngeus cartilaginous blends with elevates the pharynx and(pharyngeal plexus) part of the palatopharyngeus larynx and opens the auditory tube muscle orifice of the auditory tube during swallowingPalatopharyngeus hard palate lateral wall of tenses the soft palate and and palatine pharynx pulls the walls of the aponeurosis pharynx superiorly, anteriorly and medially during swallowing
    25. 25. Muscles Controlling the Laryngeal Inlet Intrinsic Origin Insertion Action Muscles Interarytenoid muscular process posterior surface of draws arytenoid m., oblique of the arytenoid the contralateral cartilages together, cartilage arytenoid cartilage, adducting the vocal (RLN) near its apex folds (closure of glottis) Thyroepiglottic inner surface of lateral surface of the draws the epiglottic (ELN) the thyroid epiglottic cartilage cartilage downward cartilage near the laryngeal prominence
    26. 26. Muscles Controlling Movements of the Vocal Cords Intrinsic Origin Insertion Action MusclesCricothyroid arch of the cricoid inferior border of the draws the thyroid(ELN) cartilage thyroid cartilage cartilage forward, lengthening the vocal ligaments, tenses vocal cordsThyroarytenoid inner surface of the lateral border of the relaxes and adducts(vocalis, ILN) thyroid cartilage arytenoid cartilage the vocal foldsLateral arch of the cricoid muscular process of Adducts the vocalcricoarytenoid cartilage the arytenoid cartilage cords by rotating the arytenoid cartilage(ILN)
    27. 27. Intrinsic Origin Insertion Action MusclesPosterior posterior surface of muscular process of Adducts the vocalcricoarytenoid the lamina of the the arytenoid cartilage cords by rotating the cricoid cartilage arytenoid cartilage(ILN)Interarytenoid m., posterior surface of posterior surface of Closes posterior parttransverse (ILN) the arytenoid the contralateral of rima glottidis by cartilage arytenoid cartilage approximating arytenoid cartilages
    28. 28. Nerve Supply Supplied by Vagus nerve:  Superior laryngeal n.  Internal branch (sensory and autonomic) – areas above the vocal folds including its sup. Surface (pierces the thyrohyoid membrane with sup. Laryngeal A. and lymphatics)  External branch (motor) Motor – Cricothyroid muscle  Recurrent laryngeal n., inferior laryngeal n. (sensory, motor fibers from CN XI)  Motor – all intrinsic laryngeal muscles of SAME side (except cricothyroid) and interarytenoid muscle of BOTH sides  Sensory – areas below the vocal cords
    29. 29. Recurrent laryngeal nerve is vulnerable to damage duringthyroidectomy, carotid endarterectomy, etc. because its ascendsin the groove between trachea and oesophagus and itsrelationship to the medial surface the thyroid gland Damage may cause temporary aphonia, reduction of the voiceto a whisper, choking of food and laryngeal obstruction
    30. 30. Blood Supply Upper Larynx External carotid artery Superior thyroid artery Superior laryngeal artery Lower Larynx Subclavian artery Thyrocervical artery Inferior thyroid artery Inferior laryngeal artery
    31. 31. Venouos Drainage Upper Larynx Superior laryngeal vein Superior thyroid vein Internal jugular vein Lower Larynx Inferior laryngeal vein Inferior thyroid vein Innominate vein
    32. 32. Lymphatic Drainage Superior to vocal cords Lymph vessels accompany superior laryngeal artery through thyrohyoid membrane to upper deep cervical lymph nodes Inferior to the vocal cords Through the prelarnygeal, pretracheal, and paratracheal lymph nodes to lower deep cervical lymph nodes
    33. 33. Mucous Membrane Stratified squamous epith.: over vocal cords and upper part of vestibule of larynx Ciliated columnar epith.: remainder of the cavity Mucous glands:  Ventricles and sacculi  Posterior surface of epiglottis  Margins of aryepiglottic folds
    34. 34. Basic Functions Protection Respiration Phonation Fixation of chest Closure of glottis
    35. 35. Protection Acts as a sphincter  Closure of the laryngeal inlet  Closure of the glottis  Cessation of respiration  Cough relfex, expulsion of secretions and foreign bodies
    36. 36. Respiration Assists in regulation of gaseous exchange with the lung and maintenance in acid-base balance Glottis opens a fraction of a second before air is drawn in by descent of the diaphragm  Posterior cricoarytenoids  Phasic inspiratory abduction  Synchronous w/respiration  Cricothyroid muscle  Phasic inspiratory contraction/adduction  Increases AP diameter of glottic chink
    37. 37. Phonation Voice produced by vibration of the vocal cords Fundamental tone produced at the larynx Modified by resonating chambers of the upper aerodigestive tract
    38. 38. Phonation Cricothyroid muscles  Thyroarytenoid muscles  Position the vocal cords  Provide finer isometric near the midline modifications  Lengthens true cords as  Increases internal pitch increases tension of true cord, producing cord thinning
    39. 39. Thank You